Hydraulic change-speed gearing



oct. 2s, 1930. K STRECKERT 1,779,757

,HYDRAULIC CHANGE SPEED GEARING Filed June 22, 1928 2 Sheets-sheet 1 k1 C12 a2 i Z Oct. 28, .1930. K. srREcKER-r HYDRAULIC CHANGE SPEED GEARING Filed June 28', 1928 2 Sheets-ShedI 2 I .PatentedOec 28, 1930 l' UNITED STATES PATENT ori-*ica mi. s'rnncxnn'r, oir xmnsnnnE-GRUNWTNKEL, GERMANY CHANGE-SPEED Giannina Application 'led June 28, 1928, Serial No. 288,895, and in German-y `June 29, 1927.

My invention relates todimprovements in hydraulic change speed gearings, and more particularly in gearings of the type comprising-a rotary pump and a rotary motor oper- 5 atively connected with each other and enclosed in a revolving casing, the drum of the pump being Aconnected with the driving shaft and the casing with the driven shaft,-mean'sv being further provided for controlling the 1o Iiow of the motive fluid from Vthe pump to the motor s that either the said flow is interrupted and both shafts are directly coupled with each other, or the fluid I'lows from the pump to the motorv for transmitting th -power at the desired ratio.

One of the objects of the improvements is to provide automatic means for controlling vthe flow of the motiveuid sothat the gear ratio can be continuously varied within 2o broad limits, and with this object in view my invention consists in constructing the'rotary motor so that its working chamber is varied in accordance with the-resistance opposed to the driven shaft, by varying the eccentricity of the casing of the motor and its drum.

` For directly coupling the driving shaft and the driven shaft w'ithout making Ause of the transmission of power by the motive fluid the casing of the motor is set concentrically of` so the drum, so that the active working chamber is zero, while the4 casing ofthe motor is set more and vmore into ,eccentric position in the degree as the pressure of the motive liuid is increased, sothat an increasing volume of motive uid ilows through the system result.- ing in an increasing difference ofthe velocities of the driving and driven shafts. The

construction is such that the motive\ fluidl flowingfthro'ughv the motorV causes anl addimoment is added tothe moment transmitted thereto by' the coupling action of the system, so that the resultant moment of force acting on the driven shaft'is increased as compared to the'moment of the driving shaft.

For the purpose of explaining the invention-two examples embodying the same have """been shown-in the accompanyingdrawings in 6o which the same reference characters have u tional moment of the driven .shaft,= which been used inall the Views to indicata corresponding parts. In said drawings,

Fig. l is a sectional elevation showing the improved change speed gearing,

Figs. 2 and 3 are sectional elevations taken on the lines Qf-2 and 3--3 of Fig. land looking in.the direction of thearrows,

Fig. 4 is a detail sectional view taken on line 4 4 of F ig. land showing. the mecha' cylindrical casing g having the driving shaft a1 concentrically mouirted therein, the said shaft being supported with both ends in the heads of the casing g. The casing g is rigidly connected with the driven shaft b, and it is lled with a'suitablemotivei'luid such as oil. Near. the inner end a drum t1 is fixed to or made integral with the driving shaft a1, which drum is provided with radially movable vanes 1:1, and the drum and vanes are rotatable within a vcasing Z1 disposed within the casing g. 4In its heads the casing Z1 is provided with-intake openings o1 communieating with. the inner' part of the .casing g, and in its cylindrical wall it is provided with an opening d? communicating with a pipe d disposed longitudinally of the casing g. The pipe d is closed 'atl its left hand end, and it is passed through a cylindrical bore Z' of the casing Z1 thus providing asbearing for the said casing Zlpermitting rocking movement thereof within a plane transverse of the driving shaft a1.\ l

At its right hand end'the pi e d is fixed to or made integral with the le hand head of a casing Z2 disposed within the casing g,

the opposite headof the said casing being provided with a trunnion e disposed coaxially -of the pipe d and rockingly mounted in a bore ofthe right hand head of the casing. g. Thus, the casing Z2 is likewise capable of rocking movement about the axis of the pipe d. The casing Z2 is formedy with a passage d in alignment and communicating with the i walls of the casings ipe d and further opening into the casing l. Further, the casing Z2 is provided wit an' opening ozopening into the casing g.

Within the casing Z2 there is a drum t2 p'rovided lwith radially movable vanes k2, the said drum being fixed to or made integral with a.

hollow shaft a2 concentrically mountedcon the driving shaft a1, and projecting through the right hand head of the casin g. To the outer end ofthe said hollow shag a disk Z is fixed on which spring-pressed-pawls 4a are rockingly mounted which are adapted for engagement with ratchet-teeth p provided on a rame P of the apparatus, the said pawl and ratchet teeth permitting rotation of the drum t? only in the direction of the rotation of the shaft a1.

The

f1 fixed wit one end to the -inner face of the casing g and loosely engaging with its opposlte en d a nose g1 projecting mwardly from the cylindrical wall of said casing.

The median 'part of the spring bears on aA lug m1 projectingoutwardly from the cylindrical wall ofthe casing Z1. Diametrically opposite to the piped providing the pivot of .the casing Z1, the said casing is formed with a transverse cylinder C1 having a plunger c1 mounted therein, which plunger bears on a bolt w1 fixed to the left hand head of the casing g; The cylinder ,C1 communicates through a passage 'v1 made in the cylindrical wall of the casing Z1 with the pressure chamber D provided withinthe pipe d, so that 35 the plunger c1 is alwaysacted upon by the fluid pressure within the chamber D. The power of-the spring f1 is such that it holds the casing Z1 in the position shown in Fig. 2 and eccentric -to the drum t1, as long as the fluid pressure within the chamber D is below acertain value, the eccentricity of the casing being determined by the bolt :v1 engaged `by the plunger c1. YThe casingJz is acted upon by a leaf spring f fixed with. one end to the cylindrical wall of the casing g and loosely engaging with its opposite end a lug g2 projecting inwardly from the ycylindrical wall of the said casing, the median part of the said spring bearing on a lug m projecting outwardly from the cylindrical wall of the casing Z2. Diametrically opposite to the pipe d the casing Z2 is formed with atrans# verse cylinder C? containing `a plunger c bearing on an abutment fixed to the right hand head of the casing g. The cylinder C2- -communicates -with the pipe d through a pipe fv. Lugs r and y engaging each other and provided respectively on Athe cylindrical and^Z2 hold the casing O Z acted upon by the spring f1 in the position concentric to theldrum t, as is shown in Fig.

3. But in lieu of the said abutments r andy y the plunger 'c' canbe made to bear on the bottom of the cylinder'C thus providing thel casin Z1 is actediupon by a leaf spring The strength of the springs" f1 and f2 -is not the same,` but it is such that the casing Z2 is ^displaced by a lower pressure of the motive fiuid than the casing Z1.A

At the top part of the casing Z1 there is a safety valvev z.

The operation of the gearing is as follows:

If the parts are in the positions shown in the figures, and the driving shaft a1 is rotated in the direction of the arrows shown in Figs. 2 and 3, the drum t1 tends to take liquid from the casing g through the intake openings o1 and to force the same through the opening d1 in to the pressure chamber D. Since the receive the liquid. Therefore the said liquid.l

is arrested "within the chamber D, and it prevents rotation of the drum t1 relatively to the casing Z1, so that the said casing and the casing g take part in the rotary movement of the driving shaft, and thel driven shaft b rotates at thesame velocity as the driving shaft'a1. The drum t2 takes part in the said rotation, the said rotation being not interfereld with by the pawl a and the ratchet teet p. 7

The pressure of the liquid withinthe chamber D depends on the load of the driven shaft b, which pressure is transmitted through the passages v1 and v2 to the cylinders C1 and C2. If. upon @an increase of the load of' the Idriven shaft b 'the ressure of the motive iuid is increased so ar that the pressure on thegy plunger c2 exceeds the tension of the spring f2, the casing Z2 is rocked against the action of the spring f2 into eccenarrows 2 and 3).. Therefore the drum t2 tends to rotate in a direction opposite to the direction of rotation of the driving shaft a1. But thesaid rotation is prevented by the locking mechanism a, p, and the drum t2 remains stationary. Therefore the pressure of the fluid can act only on the casing `g in the direction of the rotation of the shaft a1, so that a moment is transmitted to the shaft b which' is added to the moment transmitted from t1, l1. Therefore, the moment transmitted to the driven shaft b is increased in accordancelwith the moment of the'load acting thereon.

If the maximum tween the drum t2 and its casing'Z2 has been attained, andthe moment of the load acting on the driven shaft b is not yetcompletely' compensated, the motive fiuid acting on the 4 12; of the eccentricitybeplunger c1 reduces the eccentricity ofthe drum t1 relatively to its casing Z1 while bending the spring f1. Therefore-the active vane surface ofthe drum t1 is reduced, so that the pressure of the fluid within the chamber D and therefore the moment transmitted to the driven shaft b are further increased without increasing the moment of the driving shaft a1.

Upon a reduction of the moment of the load acting on the driven shaft b'the pressure Within the chamber D is reduced, and the spring f1 returns the drum t1 and the casing Z1 into the normal position of highest eccentricity, and thereafter the drum t2 and its casing Z2 are again set into.`position concentric to each other. The pressure on the locking mechanism z, p is relieved, and the drum 152 is again carried along by the casing Z2 in the direction of the rotation of the shaft a1 by the inner friction of the motive fluid,

, and there is no relative movement of the inner parts of the gearing.

In the modification shown in Figs. 5 and 6 a single intake opening o5 is made in the cylindrical wall of the pumpcasing Z5, and the' controlling cylinder C5 of the said casing is located at the side of the casing diametrically opposite to the point of attachment of the spring f5. The springs f5 and f5 are in the form ofcurved springs acting' by tension, and they are fixed with one end to the casing g5, and at their o'pposite ends they act on the casings Z5 and Z6 respectively, the spring f bearing on a lug g5 formed on the casing Z5, and the spring f5 engaging, with its hooksliaped end f5, a nose h5 of a lever h5 rockingly mounted on the casing Z5 at f1.5 and carrying a Weighted body hl.

The construction shown in Figs.l 5 and 6 is important when the load o'n the driven shaft b is very high, for example when starting the system. While at the beginning of the operation the number of revolutions of the casing g5 is small, the weighted body la7 is held by the spring f5v in position adjacent to the casing Z5. The tension of the spring f5 iscomparatively small, so that the casing Z5 is adapted to be rocked, by the pressure within the cylinder C5, from the position of highest eccentricity shown in-Fig. 5 towards concentric position. The result of the said displacement is a reduction of the fluid supply and an increase of the pressure thereof during the starting period.

The mass Iof the Weighted body k7, andthe ratio ofthe levers of its centre of gravitation and the point where the spring f5 acts on the lever h5 relatively to the pivot h5 are such rellatively to the tension of the spring f5, `that the Weighted body k7 begins to be rocked when i fluid within the cylinder C!1 into the position of the highest eccentricity. i

,As appears from Fi 6,the outlet 050i.-

the motor casing Z5 is a apted to be closed, so that in case of direct drive the fluid obstructing action of the motor on the fluid set under pressure by the pump is vinsured also if the casing of the motor is notexactly symmetrical relatively to the drum. `As shown, the casing Z is provided with a controlling face s disposed concentrically of the pivot of the 'casing Z, the said face being engaged by lugs n projecting inwardly from the cylindrical wall of the casing g5. The said lugs n are disposed and dimensioned so that they are adapted completely to close the two parts of thev opening o6 when the casing Z5 is in medianposition. Thespaceprovidedbetween the said lugs 'n is open in axial direction, so that the liquid is free to circulate through the said space. By subdividing the opening a8 into tWo parts it can be completely laid open by a comparatively small rocking movement of the casingZ".

While in describing the invention reference has been made to particular examples embodying the same I wish it to be understood that my invention is not limited to the ,constructions shown in the drawings, and that varlous changes may be made 1n the gen-1 eral arrangement of the apparatus and the construction of its parts Without departing from the invention.

I claim: i p

1. A change speed gearing, comprising a driving member and a driven member, a rotary pump and a rotary motor each comprising a casing, a drum mounted therein and radially movable vanes,'said pump and motor being carried by said driven member and having their intakes and outlets connected with each other for causing circulation of a motive fluid from said pump to said motor and from said motor to said pump, the drum of said pump being connected with said driving member, means to lock thevdrum of said motor against rotation in a directioan opposite to the rotation of said driving member, and means controlled by the pressure of the motive fluid for varying the positions of said drums relatively to their casings from centric positions to eccentric positions, said means being constructed so that the eccentricity' of the motor is increased and that of the pump reduced upon an increase of the said pressure.

2. A change speed gearing, comprising a driving member and a driven member, a casing carried by saiddriven member, a'rotary pump and a rotary motor mounted within said casing, a pipe Within said casing parallel to the axis thereof, the casings of said pump and motor being rockingly mounted on said pipe and having the outlet of the pump and the intake of the motor communiveo eating therewith, the drum of said pump being connected with the driving member and the drum of the motor being capable of rotation only in the direction of the rotation of the driving member, and means acted upon by the pressure of the motive fiuid for varying the eccentricity of the'motor drum relatively to its casing.

3. A change speed gearing, comprising a drivingmember andadriven member, a casing carried by said driven member,'a rotary pump and a rotary motor mounted within said easing, a pipe within said easing parallel to the axis thereof, the casings of said pump and motor being rockingly mounted on said pipe and having the outlet of the pump and the intake of the motorcommunicating therewith, the drum of said pump being connected with the driving member and the drum of the motor being capable of rotation only in the direction of the rotation of the driving member, and means operated by the pressure o f the motive fluid for varying the eccentricity of said' drumsrelatively to their casings.

4. A change speed gearing, comprising a driving member and a driven member, a casing carried by said driven member, a rotary pump and a rotary motor mounted within said easing, a pipe within said easing parallelto the axis thereof, the casings of said pump and motor being rockingly mounted on said pipe and having the outlet of the pump and intake of the motor .communicating therewith, the drum of the pump being connected with the driving member and the drum of the motor being capable of rotation only in the direction of the rotation of the driving member, a spring acting on the casing of said pump and tendingto set the.

pump casing relatively to its drum'in a position of high eccentricity, a spring acting on the casing of said motor and'tending to set said casing relatively to its drum in centric position, and means acted upon by the pressure of the motive fiuid and operative in opposition to said springs for varying the positions of the pump and motor casings relatively tortheir drums. f

5. A change speed gearing, comprising a driving member and a driven member, a rotary pump and a rotary motor carried by said driven memberand connected with each other for having a motive fluid circulating from said pump to said motor and from said motor to said pump, the drum of said pumpl being connected with said driving member and the drum of said motor" being capable of rotation only in the direction of the rotation of said driving member, a spring acting on the casing of said pump andtending to set the same relatively to its drum in a position of highest eccentricity, a weighted body rockingly mounted on said pump easing and having a spring acting thereon eccentrically of its pivot, and means operative by the pressure ofthe motive fluid and acting in opposition to said spring for varying the eccentricity of said pump casing relatively to its drum.

6. A change speed gearing, comprising a driving member and a driven member, a rotary pump and a rotary motor carried by said driven member and connected with each other for havingla motive Huid circulating therethrough, the drum of said pump being connected with said driving member, and the drum of said motor being capable of rotation in one direction only, means controlled by the pressure of the motive fluid for varying the position of said motor drum relatively to its casing from centric position to eccentric position, and means operative in the centric position of said motor drum for closing the outlet of the motor.

7. A change speed gearing, comprising a driving member and a driven member, a casing carried by said driven member, a rotary pump and a rotary motor mounted within said casing, the casing of said motor being rockingly mounted within said easing carried by the driven member for varyin the -eccentricity of the motor casing relatively to its drum from centric position to eccentric position, the drum of said pump being connected with said driving member, and the drum of said motor being capable of rotation 'in' one direction only', said pump and motor being connected with each other for having a motive fiuid circulating therethrough, the outlet of said motor being made in the cireumferential Wall of the lmotor casing and ending in a face disposed eoncentrically oi the pivot of said motor casing, a portion projecting from said casing carried by said driven memberinto position for closing said outlet from the motor when the motor drum is in centric position, and means controlled by the pressure of the motive fluid for varying the eccentricity of said motor casing relatively to its drum.

8. A change speed gearing, comprising a driving member and a driven member, a easing carried by said driven member, a rotary pump and a rotary motor mounted within said casing, the casing of said motor beingrockingly mounted within said casing carried by the driven member for varying the eccentrieit of the motor easing relatively to its drum rom centric position to eccentric cumferential wall of the motor casing and comprising a plurality of eircumferentially spaced sections ending in a face disposed concentrically` ofthe pivot of said motor cas driving member and the drum of the motor ing,'port1 ons projecting from said casing being capable of rotation only `in the direccarried by said driven member into position tion of rotation of the fdriven member, and for closing said sectional outlets from the means acted-upon by the pressure of the mov motor when the motor drum is in centricppotive iiuid for varying the eccentricity of the sition,I and means controlled bythe pressure pump and motor drums relativelyd to thelr of the motive iuid for varying the eccentriccasings'.

ity of said motor casing relatively to -itsdrum. L

9. An automatic change speed gearing, comprising a driving shaft and a driven sha-ft .a gear casing connected with said driven shaft, said shafts and casing being coaxially arranged, a rotary pump and a rotary motor enclosed insaid casing, the rotor of said pump being connected with said driving shaft, theV I casings of said pump and motor being suspended within said lgear casing' for inde-l pendent rocking movements transverse to the `shafts and being hydraulically connected in a closed circuit, and means for producing the said rocking movement by variations in Huid ressure.

10,'An automatic change speed gearing, comprising a driving member and a driven member, a rotary pump and a rotary motor A each comprising a casing and a piston drum of variable relative eccentricity, means for hydraulicallyconnecting said pump `and motor in a closedcircuit, means for varying the said eccentricity dependent on the fiuid pre'ss -snre but independent'of each other, the piston drum of. the pump being connected to the driving member, a gear casing enclosing.

said pump andmotor, said gear casing being connected to the driven member, said-pump casing and motor casing being rockingly eoV mounted within said gear casing, and means i' adapted to hold the drum of said motor against rotation in one direction. v11. An automatic change speed gearing comprising a driving member andadriven member, a gearcasing carried by said driven member. a rotary motor and a rotary pump enclosed in said gear casing. the casing of said rotary motor being rockingly mounted within said gear casing, means hydraulically connecting said ump and motor casingsin a closed circuit. the drumof said pump being/ connected with the driving member and the drum of the motor being capable of rotation only in the direction of rotation of the driven member'. and means acted upon by the pressure of themotive fluid for varying the eccentricity casing. 1 12. automatic changefspeed gearing, comprising-a driving member and a driven member, a gear `casing carried'bysaid driven member, a rotary pnmp and a rotary motor 'y enclosed in said gear casing, the casings of said pump and motor being rockingly mount-i ed wrthm said gear casing, and being hydrauhcally connected,` in .a closed circuit, the

of said pumpbeing' connected with the.

of the motor drum relativelyI its nur 

